1. Field of the Invention
The present invention relates to an optical integrated apparatus or device used in an optical pickup apparatus for optically reproducing information recorded on a record medium, such as a CD (Compact Disc), a LVD (Laser Vision Disc) and the like, or optically recording the information onto the record medium.
2. Description of the Related Art
As disclosed in Japanese Patent Application Laid Open No.Hei-4-89634, as one type of the above-mentioned optical pickup apparatus, there is an apparatus which has a semiconductor laser as a light emitting device on a semiconductor substrate on which a phase film layer, a polarization film layer, a diffraction grating, a light guide path and a first light receiving portion are laminated, and that further has a second light receiving portion at an end of the light guide path.
In this optical pickup apparatus, when the laser light is irradiated from the semiconductor laser to the phase film layer at a predetermined depression angle, the laser light is transmitted through this phase film layer, is reflected on a surface of the polarization film layer, and is collected and projected onto an information surface of an optical disc. Then, the laser lights, which are diffracted and reflected on the information surface of the optical disc, are transmitted through the phase film layer and the polarization film layer, and are inputted to the diffraction grating. Most of the reflected laser lights become the transmitted lights which are transmitted through this diffraction grating and are sent below the substrate. The remainders thereof become the guided lights guided or propagated through the light guide path. The transmitted lights are received by the first light receiving portion. A tracking error signal, an RF (Radio Frequency) signal and the like are generated by this first light receiving portion. Also, the guided lights are received by the second light receiving portion formed at the end of the light guide path. A focus error signal is generated by this second light receiving portion.
According to this optical pickup apparatus, respective constitutional elements are integrated in a process of manufacturing the semiconductor substrate, which enables the whole apparatus to be compact, and also enables the improvement of an effective utilization efficiency of the light quantity.
However, in the above-mentioned conventional optical pickup apparatus, the second light receiving portion for generating the focus error signal has such a special positional relation that it is equipped vertically with respect to the light guide path and the first light receiving portion for generating the RF signal. This results in a problem that a general light receiving device cannot be used for the second light receiving portion.
As a result, in order to manufacture this optical pickup apparatus, it is necessary to newly manufacture the light receiving portion itself as a second light receiving portion. Moreover, the manufacturing process is relatively complex because of the above mentioned special positional relation as for the second light receiving portion. Thus, this also results in a problem of the increase of the manufacturing cost of the optical pickup apparatus.
It is therefore an object of the present invention to provide an optical integrated apparatus for an optical pickup apparatus, which can achieve an integration by using a process of manufacturing a semiconductor substrate to thereby make the whole apparatus compact and improve the utilization efficiency of the light quantity, and can effectively utilize the existing manufacturing apparatus or method to thereby allow its easy manufacture and reduce its manufacturing cost.
The above object of the present invention can be achieved by a first optical integrated apparatus used in an optical pickup apparatus which irradiates a light emitted by a light emitting device to an optical information record medium, on which record information is recorded, and receives a reflection light reflected from the optical information record medium. The first optical integrated apparatus is provided with: a substrate; a light wave coupler for respectively generating a transmitted light and a guided light out of the reflection light; a light guide path for propagating the guided light; a first light receiving portion for receiving the transmitted light; and a second light receiving portion for receiving a radiant light which is generated out of the guided light and is directed toward the substrate due to a phase matching from the light guide path. The light wave coupler, the light guide path, the fist light receiving portion and the second light receiving portion are laminated on the substrate. The first light receiving portion and the second light receiving portion are formed in a same layer on the substrate.
According to the first optical integrated apparatus of the present invention, the light irradiated onto the optical information record medium, which is emitted from the light emitting device, is reflected by the optical information record medium. Then, the reflected light thereof is inputted to the light wave coupler of the optical integrated apparatus. The light wave coupler generates the guided light and the transmitted light out of the reflected light. The transmitted light is received by the first light receiving portion. On the other hand, the guided light is propagated through the light guide path and is irradiated from the light guide path by the phase matching toward the substrate so that the second light receiving portion receives it as the irradiated light. In this manner, the reflected light from the optical information record medium passes through the light wave coupler, the light guide path and the first or second light receiving portion. Since the light wave coupler, the light guide path and the first light receiving portion as well as the second light receiving portion are laminated on the substrate and since the first light receiving portion and the second light receiving portion are in the same layer, the first optical integrated apparatus can be easily manufactured by a planar technique such as a semiconductor manufacturing technique or an IC (Integrated Circuit) manufacturing process, and the manufacturing cost can be reduced. Also, the first optical integrated apparatus can be miniaturized while improving the light effective utilization efficiency.
In one aspect of the first optical integrated apparatus of the present invention, the first light receiving portion generates signals respectively corresponding to the record information and in-plane position information of the emitted light with respect to the optical information record medium, and the second light receiving portion generates a signal corresponding to focal point information of the emitted light on the optical information record medium.
According to this aspect, among the reflected light from the optical information record medium, the transmitted light generated by the light wave coupler is received by the first light receiving portion. The signal to read the record information and the signal to read the in-plane position information can be generated on the basis of the output of the first light receiving portion. On the other hand, among the reflected light from the optical information record medium, the guided light generated by the light wave coupler is propagated through the light guide path and is received by the second light receiving portion as the irradiated light toward the substrate from the light guide path by phase matching. Then, on the basis of the output of the second light receiving portion, the signal to read the focal position information is generated. As mentioned above, since the signal to read the record information and the signal to read the in-plane position information can be generated on the basis of the transmitted light having the enough intensity, those signals can be generated as having good qualities. Further, since the signal to read the focal position information of the irradiated light with respect to the optical information record medium can be generated by the guided light, which is propagated through the light guide path and which can reserve an enough light propagation length, a subtle change of the irradiated light on the optical information record medium can be detected as a large optical change at the second light receiving portion. Namely, the signal to read the focal position information can be generated as having good signal quality.
The above object of the present invention can be also achieved by a second optical integrated apparatus used in an optical pickup apparatus which irradiates a light emitted by a light emitting device to an optical information record medium, on which record information is recorded, and receives a reflection light reflected from the optical information record medium. The second optical integrated apparatus is provided with: a substrate; a light wave coupler for respectively generating a transmitted light and a guided light out of the reflection light; a light guide path for propagating the guided light; a first light receiving portion for receiving the transmitted light; and a second light receiving portion for receiving a radiant light which is generated out of the guided light and is directed toward the substrate due to a phase matching from the light guide path. The light wave coupler, the light guide path, the fist light receiving portion and the second light receiving portion being laminated on the substrate. The first light receiving portion and the second light receiving portion being disposed independently from each other on the substrate. The first light receiving portion generating signals respectively corresponding to the record information and in-plane position information of the emitted light with respect to the optical information record medium. The second light receiving portion generating a signal corresponding to focal point information of the emitted light on the optical information record medium.
According to the second optical integrated apparatus of the present invention, the light irradiated onto the optical information record medium, which is emitted from the light emitting device, is reflected by the optical information record medium. Then, the reflected light thereof is inputted to the light wave coupler of the optical integrated apparatus. The light wave coupler generates the guided light and the transmitted light out of the reflected light. The transmitted light is received by the first light receiving portion. On the other hand, the guided light is propagated through the light guide path and is irradiated from the light guide path by the phase matching toward the substrate so that the second light receiving portion receives it as the irradiated light. In this manner, the reflected light from the optical information record medium passes through the light wave coupler, the light guide path and the first or second light receiving portion. Since the light wave coupler, the light guide path and the first light receiving portion as well as the second light receiving portion are laminated on the substrate, the first optical integrated apparatus can be easily manufactured by a planar technique such as a semiconductor manufacturing technique or an IC (Integrated Circuit) manufacturing process, and the manufacturing cost can be reduced. Also, since the first light receiving portion and the second light receiving portion are disposed independent from each other, the signal to read the record information of the optical information record medium and the signal to read the in-plane position information can be generated on the basis of the transmitted light having enough intensity. Namely, those signal can be generated as having good signal qualities. Further, since the signal to read the focal position information of the irradiated light with respect to the optical information record medium can be generated by the guided light, which is propagated through the light guide path and which can reserve an enough light propagation length, a subtle change of the irradiated light on the optical information record medium can be detected as a large optical change at the second light receiving portion. Namely, the signal to read the focal position information can be generated as having good signal quality.
In one aspect of the second optical integrated apparatus of the present invention, the first light receiving portion and the second light receiving portion are formed in a same layer on the substrate.
According to this aspect, since the first light receiving portion and the second light receiving portion are in the same layer, the first optical integrated apparatus can be easily manufactured by a planar technique, and the manufacturing cost can be reduced.
In another aspect of the first or second optical integrated apparatus of the present invention, the substrate comprises a semiconductor substrate.
According to this aspect, the first or second optical integrated apparatus can be easily manufactured by a planar technique such as a semiconductor manufacturing technique or an IC (Integrated Circuit) manufacturing process, and the manufacturing cost can be reduced.
In another aspect of the first or second optical integrated apparatus of the present invention, the first light receiving portion is mounted at one position directly beneath the light wave coupler in a lamination direction of the optical integrated apparatus or at another position in a vicinity of the one position.
According to this aspect, among the reflected light from the optical information record medium, the transmitted light generated by the light wave coupler is received by the first light receiving portion. Since the first light receiving portion is mounted at one position directly beneath the light wave coupler in a lamination direction of the optical integrated apparatus or at another position in a vicinity of the one position, the first light receiving portion can receive the transmitted light which transmits the light wave coupler and has a strong intensity. Therefore, the signal can be generated as having the good signal quality on the basis of the output of the first light receiving portion. Further, it becomes possible to dispose the first light receiving portion at a position of the far-field with respect to the light emitting device, so that a stable signal generation can be performed while reducing the influence of the positional displacement or shift of the light emitting device.
In another aspect of the first or second optical integrated apparatus of the present invention, the second light receiving portion is mounted on a front side, in a propagation direction of the guided light, of a position of the light wave coupler, the optical integrated apparatus further comprises an insulation buffer layer disposed between a layer of the second light receiving portion and a layer of the light guide path, the buffer layer has an inclined surface to reduce a layer thickness of the buffer layer from a predetermined position on a side of the light wave coupler to a position above the second light receiving portion.
According to this object, among the reflected light from the optical information record medium, the guided light generated by the light wave coupler is propagated through the light guide path and reaches the position of the second light receiving portion, which is mounted on a front side, in a propagation direction of the guided light, of a position of the light wave coupler. At this time, the insulation buffer layer is disposed between a layer of the second light receiving portion and a layer of the light guide path. The buffer layer has an inclined surface to reduce a layer thickness of the buffer layer from a predetermined position on a side of the light wave coupler to a position above the second light receiving portion. Therefore, the layer thickness of the buffer layer above the second light receiving portion is thinner than that of the other portions thereof, so that the guide light propagated through the light guide path is irradiated from the light guide path certainly with enough power, to be received by the second light receiving portion. In this manner, since the light is propagated by the light guide path which can reserve an enough light propagation length and since the light, which is irradiated certainly with enough irradiation power, is inputted to the second light receiving portion with enough light intensity, it is possible to perform the generation of the signal with high sensitivity and high quality.
In another aspect of the first or second optical integrated apparatus of the present invention, the first or second optical integrated apparatus is further provided with a light path separation layer disposed at a top layer of the optical integrated apparatus for separating a light path of a light incident to the top layer into one path for the reflected light to an outside portion of the optical integrated apparatus and another path for the transmitted light to an internal portion of the optical integrated apparatus. The light separation layer comprising a multiple-layered film of dielectric material.
According to this aspect, the light emitted from the light emitting device is inputted to the light separation layer formed at the top layer of the first or second optical integrated apparatus. The light separation layer reflects the incident light to thereby generate the irradiation light toward the information record surface of the optical information record medium. On the other hand, the light returned from the optical information record medium is inputted to the light separation layer through the same path for the irradiated light toward the optical information record medium. Then, the light separation layer transmits this returned light to the internal portion of the first or second optical integrated apparatus. The light separation layer comprising a multiple-layered film of dielectric material, changes the phase of the light emitted from the light emitting device by appropriate degrees, and transmits the light having an appropriate mode to the internal portion of the first or second optical integrated apparatus. Therefore, it is possible to appropriately perform the light receiving operation by each light receiving portion as described above.
In another aspect of the first or second optical integrated apparatus of the present invention, the first or second optical integrated apparatus is further provided with a light path separation layer disposed at a top layer of the optical integrated apparatus for separating a light path of a light incident to the top layer into one path for the reflected light to an outside portion of the optical integrated apparatus and another path for the transmitted light to an internal portion of the optical integrated apparatus. The light separation layer is provided with: a second light wave coupler for generating a guided light out of the incident light; a second light guide path for propagating the guided light generated by the second light wave coupler; and a third light wave coupler for irradiating the guided light propagated through the second light guide path to the outside portion of the optical integrated apparatus.
According to this aspect, the light emitted from the light emitting device is inputted to the second light wave coupler formed at the top layer of the first or second optical integrated apparatus. The second light wave coupler generates the guided light out of the incident light, and this guided light is propagated through the second light guide path. Then, this guided light propagated through the second light guide path reaches the third light wave coupler, is irradiated to the outside portion of the first or second optical integrated apparatus by the third light wave coupler, is passed through a xc2xc wave length plate, and is irradiated onto the information record surface of the optical information record medium. On the other hand, the light returned from the optical information record medium is inputted to the third light wave coupler through the same path for the irradiated light toward the optical information record medium. Then, the third light wave coupler transmits this returned light to the internal portion of the first or second optical integrated apparatus. A grating coupler, which is provided with the above described second and third light wave couplers and the second light guide path, propagates and reflects the light at a predetermined mode (e.g., TM mode or TE mode) while transmitting the light at a predetermined mode to the internal portion of the first or second optical integrated apparatus. Therefore, it is possible to appropriately perform the light receiving operation by each light receiving portion as described above.
In another aspect of the first or second optical integrated apparatus of the present invention, the second light receiving portion has a light receiving surface, which is formed substantially parallel to an optical axis of the guided light propagated through the light guide path, the second light receiving portion generates a signal corresponding to focal point information of the emitted light on the optical information record medium by detecting a change of an image area of the irradiated light from the light guide path on the light receiving surface based on a change of a focal position of the irradiated light.
According to this aspect, among the reflected light from the optical information record medium, the guided light generated by the light wave coupler is propagated through the light guide path and is received by the second light receiving portion as the irradiated light from the light guide path. The light receiving surface of the second light receiving portion is formed substantially parallel to an optical axis of the guided light propagated through the light guide path. Thus, if the focal position of the irradiated light from the light guide path is changed, it can be detected as the change of the image area on the light receiving surface. Namely, the change of the focal position of the irradiated light with respect to the optical information record medium can be easily and certainly detected as the change of the image area formed on this light receiving surface. Also, the adjustment of the received light at the second light receiving portion can be easily performed by changing the distance between the light guide path and this light receiving surface or by changing the size of this light receiving surface in the optical axis direction.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below.